The invention relates to a lithographic device comprising a lithographic irradiation system which has a vertical main axis parallel to a z-direction and is fastened near a lower side to a mounting member belonging to a frame of the device, and comprising a positioning device which is arranged below the irradiation system and by means of which an object table is displaceable relative to the irradiation system over a guide surface of a support member coupled to the positioning device, which guide surface extends perpendicular to the z-direction.
A lithographic device of the kind described in the opening paragraph is used for carrying out a lithographic process on a substrate positioned on the object table, such as, for example, an optical lithographic process in which the irradiation system is provided with a lens system and a light source (for example, a UV-light source), an X-ray lithographic process in which the irradiation system is provided with an X-ray source, or an electrolithographic process in which the irradiation system is provided with an electron tube. U.S. Pat. No. 4,737,823 discloses an optical lithographic device of the kind mentioned in the opening paragraph in which the irradiation system is provided with a lens system which is fastened to the mounting member near a lower side. In this known lithographic device, the support member is a rectangular granite slab which forms part of the frame of the device. Four columns of the frame extending parallel to the z-direction are fastened on the guide surface formed by an upper side of the support member, to which columns the mounting member, which is constructed as a plate extending in a direction transverse to the main axis, with the lens system is fastened at some distance above the support member. At a lower side, the support member is provided with lower frame supports, each provided with a spring member and a damping member.
A frame construction as described above results in a comparatively great constructional height of the device in the z-direction. The constructional height of the known lithographic device is determined inter alia by the height of the lens system, the height of the positioning device and the support member, and the height of the lower frame supports. Such a constructional height is disadvantageous, especially in an application of the device in a conditioned production room for, for example, integrated circuits.